The present invention relates in general to seat belt retractors and more particularly to a seat belt retractor capable of operating in severe environments such as mud and snow and rain. More particularly, the present invention provides a sealed chamber for the vehicle inertia sensor, also referred to as a vehicle sensor, which is used to initiate lock-up of the retractor.
More specifically the invention comprises: a seat belt retractor 10 having a frame with sides 14, 16 and a cover associated with at least one side, an inertial sensor positioned between the at least one side of the frame and the cover, a seal located between the cover and the frame side to prevent contaminants from entering a space about the inertial sensor, the inertia sensor including a movable mass 34 and a magnet 36 spaced from the mass 34 to create a magnetic force upon the mass 34 preventing the magnet from moving excessively if the retractor is subject to predetermined levels of vibration.